#include <string>
#include <iostream>

using namespace std;

string caesar(const string &str, int k) {
  string result;

  for (char c : str) {
    char chr = c + k;

    if (chr > 'z') {
      chr %= 'z';
      chr += 'a';
      chr -= 1;
    }

    result.push_back(chr);
  }

  return result;
}

int main(int argc, char const *argv[])
{
  /* code */
  cout << caesar("xyz", 2) << endl;
  return 0;
}
